Diaphragm.



F. B. MEECH.

DIAPHRAGM.

APPLICATION FILED 0011.4, 1910.

1,016,704. mama Feb.6,1912.

I WITNESSES [WENT R W BY ATTORNEY FRANK ".8. MEECH, (3F LJEW YGHK. :33.Y.

'IJIAPHRAGlvI.

Specification of Letters Patent. ""1; @n'l'intll 1 6 i t5. 1%}12,

Application filed October 4, 1910. Serial No. 585,975.

To (ZZZ trim-m '1' 6 may concern,

Be it lcnoivn that l. Fnmzu li. Min-mu. a citizen of the United some.residing at Ken: York. in the county and State of New York.

have invented new and useful lmprouunents in Diaphragms, of which thefollowing a speci tication.

This invention relates to sound apparalus where sound vibrations arereceived from or transmitted to a diaphragm.

More particularly the invention relates to a dia 'ihragm where. voice ormusical sound vibrations are received or utilized. such vibrations orWaves being compounded frcnn many individual sound sources or 00711130nen't vibrations, and. resulting in a complicated or intricatelycomposed ave. If the diaphragm does not respond exactly to the wave formin all its detail and complication, the purity of the sound Will helost.

One of the objects of the. present invention is to provide adiaphragm ofsuch a character that the sound purity will be preserved; in other wordsin which the sound Wave will be received or utilized Without changingits characteristics, even in the more minute or complicated details ofsound wave form.

So far as l ain aware, diaphragms have hitherto b8( i made on theprinciple of securing Inerelyhigh elasticity; mica glass, copper,aluminum or other similar sonorous substances being examples. Suchmaterials by virtue of their jelastic and sonorous character seem to heand are adapted to ve cer tain acoustic results. So far as Iain awarethe effort at inniroveInQnt has hitherto been constantly in thedirection of obtainingmaterials inore elastic and more vibratile orsonorous in character than those hitherto utilized, and the latestdevelopments are in the direction of mica as being a. material havingthe above characteristics most prominently inherent in it.

Itis one of the objects of the present in vention to utilize newprinciples of action which have not been hitherto considered as havingany hearing, or relation, and by'utilining such new principles toprovide an improved diaphragm.

The invention relates to an improved diaphragm in its various aspects.

To this end the invention cons material employed and in the co ructionsand combinations as hereinafter setforth.

in the drawings, Figure l, is a perspective view of a diaphragi'neniihodying the prineiplu'agrm:

is a. similar a modified form oil diu- 3 and l, illustrate furthermodili-z .l igrs. and (l. are rcspec tively sectional and front. viewsof another modifi d form of diaphragm mlmdving the invention, and Fi e.T, shows diagramnuiiirally the use of a diaphragm in asound 1'11"cording or reproducingapymratu The invention will include a cellulardiaphra e'ni of'a material which is light in 'sveicjht. in accordancewith the principles of vibration and motion, the inertia or weight ofanything acted upon tends to produce a lag between the cause and el .l;0. between action and the motion resi-lting from the action. 'Thereducii'ig of the pies o'l my invention: Fist. 2, View sl weight istherefore a matter of importance,

which, however, is related to other matters of equal importance. Asecond principle or attribute of my diaphragm. flexibility, meaningflexibility in ditl'erent. Ways or directions. A third principle orattribute uniformity in any elastic stress or strain put on the materialby any deformation. A.

fourth principle or attribute of the present;

diaphragm is absence of vicosity, the ideal material being one whichrecovers its -origi nal form instantly when the deforming 'influence isremoved. A fifth principle or attribute that the factors above mentioned27. c. flexibility uniform elasticity and absence of vicosity mnst bepresent particularly in deformations hi the diaphragm be tween narrowranges or limits of movement or deformation, rather than between widelimits, in order to suit the microscopic char actor of actual soundvibration.

In order to find a material satisfying the,

ahve principles and requirements, I have conducted experiments and havediscovered that cork "when out in sheet form and made into a diaphragmgives results which are not only siuierior to any results hi thei'toolotained, but are markedly different. in character, particularly withreference to the purity ofthe sound received or utilized. The inventionwill therefore in its best form include cork in the form of a diaphragmas A in Fig. 1. The actual forms, details and arrangementof the corkdiaphragm may be varied. The cork may he in its natural state. or may becompr :d. or it; may be treated or used in prepa 'ations known ascomposition cork. It may be cut in thin sheets A. Fig. 1. or thicksheets l3. 2. It

made in unitary construction asin'llig. 1, or

in sectional construction, as shown in Figs] 5 and 6. in these figuresthere is provided a plurality of sectors or sections grouped around acommon center and associated into unitary'forni by cement or otherwise.

The diaphragm may have a thickened rim portion asl Fig. 3, eitherintegral or separately applied. it may be made of tWo sheets or sectionssuch as E and F l? ig. t cemented together so as to cure thenaturalporosity of a plain corlrsheet.

The essential physical characteristic of my improved diaphragm Whichdistinguishes it from other diz'lphragins hitherto used, .is that it hasa very light comparatively honiogene' 011s cellular structure. .lnaddition to this there is the further characteristic that its tension ina given median plane of vibration Wholly dependent on its ownresiliency, or in other Words not dependent on outside factorssuch asmetal plates.

The microscopic cellular structure of n y diaphragm is such that it isalmost perfectly elastic to recover itself from deformation through aminute deflection, although when considerably deformed it does notappear to be elastic: and does not recover itself promptly. This is dueto the cellular charactor of the cork, the cells being very much like amass of bubbles of very small size and uniformly homogeneous in allplanes. A very small deflection does not bend or crush any of the Wallsbetween the cells, Which 'alls are exceedingly thin and delicate. Thevibration on the other hand is a true vibra- W tion, and the recovery ofthe cork is doubtless due to the air in the cells as Well as theresiliency of their delicate cellular Walls.

In accordance With'my present diaphragm the stiffness is secured not bytensioning the diaphragm, but by making it quite thick, for example orof an inch in thickness.

In Fig. 7 I hiive shown diagrammatically one use of the diaphragm in asound box for sound recording and reproducing purposes. 1 denotes thesound box; 2 the diaphragm therein, and 3 the means or stylus connectedto said diaphragm for transmitting sound vib -ations. V

\Vhile l have described certain forms of diaphragm I do not desire to beparticularly limited or restricted to the particular constructionsshown, since variations may be made within the principles of theinvention,

'without departing from the spirit or scope thereof.

hat I claim is:'-

A diaphragm for sound recording and reproducing apparatus comprising adisk or plate of natural cork permanently cemcnte to a similar disk orplate of natural cork, said plates of cork being adapted to transverselystiffen one another throughout. their entire area.

in testimony whereof, I have signed my name to this specification in thepresence of two subscribing W tnesses, this 3rd day of Cctober 1910.

FRANK B. MEEGl-l.

"Witnesses GRACE T. Dixon, ALFRED W. Pnoo'ron.

